autotrace显示Statistics很多信息为0(转)

最新推荐文章于 2025-09-11 20:53:34 发布

转载最新推荐文章于 2025-09-11 20:53:34 发布 · 88 阅读

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#数据库

朋友用autotrace查看数据库执行计划，发现Statistics中很多信息为0，其中consistent gets为0属不正常现象。文中给出解决方法，即重新查看Statistics信息，并提供了相关参考链接。

一朋友使用autotrace查看数据库执行计划发现结果如下,Statistics中很多信息为0,这个肯定是不正常现象,什么都可以为0,consistent gets也不可能为0.

 
         SQL> 
         set 
         autot 
         on
        
         SQL> 
         select 
         count
         (*) 
         from 
         RACV_DATA.PARTY_DUMMY;
        
         COUNT
         (*)
        
         ----------
        
         47
        
         Elapsed: 00:00:00.00
        
         Execution Plan
        
         ----------------------------------------------------------
        
         Plan hash value: 3621440939
        
         --------------------------------------------------------------------------
        
         | Id  | Operation          | 
         Name        
         | 
         Rows  
         | Cost (%CPU)| 
         Time     
         |
        
         --------------------------------------------------------------------------
        
         |   0 | 
         SELECT 
         STATEMENT   |             |     1 |     3   (0)| 00:00:01 |
        
         |   1 |  SORT AGGREGATE    |             |     1 |            |          |
        
         |   2 |   
         TABLE 
         ACCESS 
         FULL
         | PARTY_DUMMY |    47 |     3   (0)| 00:00:01 |
        
         --------------------------------------------------------------------------
        
         Statistics
        
         ----------------------------------------------------------
        
         0  recursive calls
        
         0  db block gets
        
         0  consistent gets
        
         0  physical reads
        
         0  redo 
         size
        
         0  bytes sent via SQL*Net 
         to 
         client
        
         0  bytes received via SQL*Net 
         from 
         client
        
         0  SQL*Net roundtrips 
         to
         /
         from 
         client
        
         0  sorts (memory)
        
         0  sorts (disk)
        
         1  
         rows 
         processed

解决方法

 
         SQL>  
         select 
         owner,object_name 
         from 
         dba_objects 
         where 
         object_name=
         'PLAN_TABLE'
         ;
        
         no 
         rows 
         selected
        
         SQL> @?/rdbms/admin/utlxplan.sql
        
         Table 
         created.

重新查看Statistics信息

 
         Statistics
        
         ----------------------------------------------------------
        
         0  recursive calls
        
         0  db block gets
        
         7  consistent gets
        
         0  physical reads
        
         0  redo 
         size
        
         522  bytes sent via SQL*Net 
         to 
         client
        
         524  bytes received via SQL*Net 
         from 
         client
        
         2  SQL*Net roundtrips 
         to
         /
         from 
         client
        
         0  sorts (memory)
        
         0  sorts (disk)
        
         1  
         rows 
         processed